Unfortunately, brief conversations, especially ones involving lots of time pressure, are really tricky to address. Those sorts of situations are certainly the ones I dislike the most. While it might not really address the situation directly, I think it's easier for people to handle someone that stutters with clear, deliberate repetitions and unconstrained, stuttered speech than someone who mostly blocks and struggles against themselves to get words out. Since you've already had quite a bit of speech therapy, the only thing that can really help with that at this point is practice, whether it be practicing strategies like deliberate stuttering or simply practicing staying confident while talking. Hang in there!